why not? Everything is all balanced to 5,000 rpm. You arent going to hurt it if grade braking takes it north of 4000+ rpm. Its not a cummins, revving screaming high is fine with the V8's. It does give you a scare the first time hearing it, the dmax wind out to 4500rpm coming down a long hill.

I agree the grade braking "sometimes" doesnt work. The logic/algorithm that allison has programmed to decide when to command a downshift sucks. Sometimes it refuses to downshift no matter how much I ride the brakes coming down a hill, other times I just kiss the brake pedal with my foot and it immediately downshifts.

As for how it holds back on a hill, its no different than the engine braking capability of a manual transmission. Remember the allison is not like any other automatic. It CANT FREEWHEEL. When its in tow/haul mode, which keeps the converter locked all the time, the engine is as directly coupled to the rear wheels as it would be with a hand shaker.

As to the allison, as I said before, its completely different than any other auto, and thus is feels different too. Some people love it some hate it, to each his own. I couldnt be happier with my allison. I have 85k miles on it since I built it, all stock hard parts in it, and its holding a built motor and twin turbos no problem. IMO the (stock, mind you) cummins automatics Ive driven made me go insane. I hate how the converter unlocks as soon as you let off the throttle, and how the trans freewheels easily. 4 speeds is nowhere near enough to keep the cummins in its low end peak torque range. Just when the engine would start to lug and start pulling like a freight train, the stupid trans would downshift and ruin that awesome cummins torque. Anyway, just my opinion.

ben

 

the dmax has been basically more or less the same base design since it came out in 2001, it was the only of the big three that did not need a complete redesign for 2007 emissions. The only things they added to meet 07 emissions regs were a DPF and intake throttle body. The dmax changes throughout its 2001-2010 lifespan are more akin to say the 2004.5 updates to the 5.9 cummins. Minor things here and there but by no means a redesign.

The cummins was completely new for 2007 (ok fine yes I know it uses some parts from the 5.9), so it makes sense that they designed it to already be 2010 compliant. What I do think is awesome about the 6.7 is that it meets 2010 regs without the urea injection. Hats off to cummins on that one. The upcoming 2010 dmax redesign is going to have to use urea to meet 2010 regs.

Ford on the other hand is just plain stupid. They completely redesigned the PSD to meet 07 regs, but yet didnt look forward enough to 2010??? The 6.4 doesnt meet 2010 regs, so basically its going to be out for all of 2 years and then disappear??

ben

 

I hardly ever wrapped my old gasser up to 4K. It may be designed for those rpm's, but with that much weight pushing and it dropping gears that fast, I just don't really feel comfortable. As far as holding back, I don't think it holds back a load near as well as my 6spd does without the exhaust brake. Who knows? I might just have a lemon, but I sure haven't been too impressed so far with the Allison, nor the location of the block heater cord. The engine itself has been great so far though.

 

I would have kept the dodge honestly. other than vp issues or if you had alot of issues out of it I would have kept it. none of the new dpf diesels appeal to me at all but its your money enjoy your new truck

 

thats probably because of the long cummins stroke. The dmax is undersquare (like a gas engine HA HA : ) so its not going to provide as much compression braking.

Also, dmax heads flow much much better than cummins heads so that might affect it too. The one manual trans dmax ive ridden in didnt feel like it had great engine braking either.

If you watch everything with a scan tool coming down a long hill with a trailer in tow/haul mode, engine RPM never differs more than 25 rpm or so from output speed on the trans. Meaning, its just about as directly coupled as a manual.

I agree about the block heater cord, its stupid how they wrap it up at the factory. But once you spend an hour unwrapping it and routing it, it will reach the grille easilly. Besides, you dont really need the block heater IMO. Mine starts just fine at -25*. For what its worth...just my opinion.

ben

 

I believe the Cummins will also require Urea to be 2010 compliant, can't find the thread, but I believe we came to that conclusion.